Injection molded lab-on-a-disc platform for screening of genetically modified E. coli using liquid-liquid extraction and surface enhanced Raman scattering

We present an injection molded lab-on-a-disc enabling quantification of bacterial metabolites in E. coli supernatant.</p

Centrifugal microfluidics for cell-based assays in flow

Understanding the complex biological processes in the human body is one of the major areas of scientific interest. In order to reach a better level of understanding it is important to observe and study cells, the basic building blocks of living organisms. In the course of many years, in vitro biological models have been created in order to comprehend how cells react to certain stimuli or drugs. Nowadays for example, the screening of newly developed drugs is carried out in vitro, prior to in vivo studies. In vitro assays are rather cost efficient, rapid and user-friendly, compared to complex in vivo studies.The most used in vitro cellular models, and still the “gold standard”, are based on static cultures carried out in petri dishes or flasks. Despite their simplicity, these systems do not quite reproduce the in vivo microenvironment. However, there is a wide variety of in vitro models, based on perfusion culture which have been shown to mimic certain aspects of the in vivo environment. A well-known example is the so called Lab-on-a-Chip (LoC) platforms which allow the integration of complete laboratory protocols on a small footprint (chip) where cell cultures are grown in flow. Despite the advantages of culturing cells in perfusion and providing certain stimuli, there is still the need for complex fluidic actuation systems to facilitate fluid handling such as pumps and tubing.In the frame of this Ph.D. project, centrifugal microfluidics has been identified as a possible alternative to conventional microfluidic systems. Lab-on-a-Disc (LoD) systems only need a simple motor to actuate and control liquids. These polymer disc-shaped devices, generally fabricated using rapid prototyping techniques, can be easy to use, compact and portable point of care units. LoDs have been of great interest because they are able to combine the functional components necessary to perform complex assays into small, integrated devices (discs). However, to the best of our knowledge, long-term cell culture has not yet been established in centrifugal microfluidics.In this thesis, a compact and robust centrifugal microfluidic platform for long-term cell culture and drug testing is presented. The device, compatible with optical microscopy techniques, allows culture for multiple days (from 1 up to 7 days) depending on the flow rates (2 to 0.3 μL/min) without the need of additional liquid handling. This in vitro system was successfully used for culturing both bacterial and mammalian cells. After establishing the cell cultures, testing of different antibiotic treatments was carried out on bacterial biofilms and a cytotoxicity assay was demonstrated using mammalian cells. Additionally, real-time detection of mammalian cells was shown, using the integration of a novel miniaturized microscope on disc. The centrifugal platform proved to be a versatile device able to provide diverse in vitro conditions depending on the experiment requirements while delivering reproducible and reliable results. The user-friendly compact LoD could become an essential point of care device for the initial steps of drug screening as well for users like biologists, clinicians and pharmaceutical scientists